And I'm Steve Inskeep. Good morning. A report by United Nations' chemical weapons inspectors does not blame Syria's government for last month's chemical weapons attack. The inspectors were not authorized to do that. But they did provide substantial evidence, the most detailed look available, of an August 21 attack that led the United States to threaten military action.

Anthony Cordesman of the Center for Strategic and International Studies has been reading that report. He's on the line. Welcome back to the program, sir.

ANTHONY CORDESMAN: Thank you.

INSKEEP: So what evidence, if any, links this attack to Syria's government?

CORDESMAN: There are blood tests, there are urine tests, there are interviews of 50 people. There is a characterization of environmental samples which revealed the use of sarin.

INSKEEP: Mm-hmm.

CORDESMAN: They have found fragments of the munitions which indicate these were not explosive rockets, but carried a chemical agent.

INSKEEP: Right.

CORDESMAN: They've been able to identify the trajectory with which two types of rockets were fired. And all of this was done under conditions which, quite frankly, if you read the report are a bit amazing because the inspectors had to rush in and accomplish this in the course of hours over a period of three days under conditions of an uncertain ceasefire.

INSKEEP: You said identified the trajectory from which two types of rockets were fired, which of course helps them identify where the rockets came from. Is that a significant piece of evidence here?

CORDESMAN: Well, the problem is only outsiders can assess several key factors. One is the French has provided detailed intelligence data indicating that Syrian forces were in the general area of the trajectories.

INSKEEP: OK.

CORDESMAN: The rockets seem to be rockets we know are in Syrian hands in which Russia has armed in the past with chemical weapons. The fragments are ones which may be traceable, because there are some serial numbers, to specific deliveries to Assad forces. Outside intelligence can provide strong indications as to whether the rebels ever even had such weapons.

They can also make assessments of how many rockets needed to be fired in these areas. And these are not single rockets fired from a single launcher. They're normally deployed in 16 to 17 rockets and fired in a ripple in the course of about eight seconds. So this is not a weapon that people can have small numbers of and have a like device to launch. It takes a well structured unit to produce anything like the reported casualties.

INSKEEP: Any doubt in your mind who's responsible?

CORDESMAN: I think that at this point - you can never totally disprove a negative - but it seems overwhelmingly clear that this not only was the Assad forces but a clear decision was made to provide enough rockets and enough launchers, with combat troops associated with Syrian forces under Assad's command, to conduct a major chemical weapons attack on a civilian area.

INSKEEP: We've just got about 30 seconds here, but you mentioned the difficulty the inspectors clearly faced. What does that say about the prospect for removing Syria's chemical weapons as is now contemplated?

CORDESMAN: All of that will depend on the method. If we do it by the book it can take a long, long time. If we simply take them out to the desert and blow them up, it can be very quick. It's going to be a hard set of choices as to evidence and risk.

INSKEEP: Mr. Cordesman, thanks very much as always.

CORDESMAN: Thank you.

INSKEEP: Anthony Cordesman of the Center for Strategic and International Studies. Transcript provided by NPR, Copyright NPR.